1. Field of the Invention
The invention relates to endoscopic surgical instruments which have a proximal actuator and distal end effectors which are coupled to each other by a flexible coil. More particularly, the invention relates to a snap-fit collar for coupling the end of a flexible coil of an endoscopic instrument to the actuator or to the end effectors of the instrument.
2. State of the Art
Endoscopic surgical instruments generally include a hollow tube member having a proximal end and a distal end and a control member such as a push rod or a pull wire which extends through and is reciprocally movable in the tube member. An actuator mechanism is coupled to the proximal ends of the tube and control member, and at least one of a pair of end effectors is coupled to the distal end of the tube and control member by means of a clevis. Operation of the actuator mechanism causes the control member to move relative to the tube member which in turn causes the end effector to rotate in the clevis. The hollow tube member is often a flexible coil which permits the end effectors of the instrument to be fed through a curved or tortuous path to the surgical site. The coupling of the flexible coil to the clevis and to the actuator mechanism is most often effected by crimping.
Parent application Ser. No. 08/275,291 discloses an actuator mechanism for an endoscopic instrument which includes a stationary handle having a stepped throughbore with a relatively smaller diameter at the distal end and a relatively larger diameter at the proximal end. A cylindrical rack member is slidably disposed in the larger diameter portion of the throughbore. The larger diameter portion of the throughbore has a lower slot opening, and a movable lever is pivotally coupled to the stationary handle and is provided with a toothed upper pinion which enters the slot in the larger diameter portion of the throughbore and engages the rack member. The actuator mechanism is particularly well suited for use in an endoscopic instrument having a flexible coil tube member and a control member extending through the flexible coil. The proximal ends of the control member and the flexible coil are coupled to the actuator mechanism which imparts reciprocal movement to the control member relative to the flexible coil. The distal end of the flexible coil is coupled to a clevis within which a pair of end effectors are rotatably mounted; and the distal end of the control member is coupled to the end effectors. Several different means for coupling the ends of the flexible coil to the handle and the clevis are disclosed in the parent application, including the use of a staple and press-fit ferrule. While these couplings are effective, their assembly is time consuming and increases the cost of manufacture of the instrument.